!********************************************************************** ! Copyright 1998,1999,2000,2001,2002,2005,2007,2008,2009,2010 * ! Andreas Stohl, Petra Seibert, A. Frank, Gerhard Wotawa, * ! Caroline Forster, Sabine Eckhardt, John Burkhart, Harald Sodemann * ! * ! This file is part of FLEXPART. * ! * ! FLEXPART is free software: you can redistribute it and/or modify * ! it under the terms of the GNU General Public License as published by* ! the Free Software Foundation, either version 3 of the License, or * ! (at your option) any later version. * ! * ! FLEXPART is distributed in the hope that it will be useful, * ! but WITHOUT ANY WARRANTY; without even the implied warranty of * ! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * ! GNU General Public License for more details. * ! * ! You should have received a copy of the GNU General Public License * ! along with FLEXPART. If not, see . * !********************************************************************** function psih (z,l) !***************************************************************************** ! * ! Calculation of the stability correction term * ! * ! AUTHOR: Matthias Langer, adapted by Andreas Stohl (6 August 1993) * ! Update: G. Wotawa, 11 October 1994 * ! * ! Literature: * ! [1] C.A.Paulson (1970), A Mathematical Representation of Wind Speed * ! and Temperature Profiles in the Unstable Atmospheric Surface * ! Layer. J.Appl.Met.,Vol.9.(1970), pp.857-861. * ! * ! [2] A.C.M. Beljaars, A.A.M. Holtslag (1991), Flux Parameterization over* ! Land Surfaces for Atmospheric Models. J.Appl.Met. Vol. 30,pp 327-* ! 341 * ! * ! Variables: * ! L = Monin-Obukhov-length [m] * ! z = height [m] * ! zeta = auxiliary variable * ! * ! Constants: * ! eps = 1.2E-38, SUN-underflow: to avoid division by zero errors * ! * !***************************************************************************** use par_mod implicit none real :: psih,x,z,zeta,l real,parameter :: a=1.,b=0.667,c=5.,d=0.35,eps=1.e-20 if ((l.ge.0).and.(l.lt.eps)) then l=eps else if ((l.lt.0).and.(l.gt.(-1.*eps))) then l=-1.*eps endif if ((log10(z)-log10(abs(l))).lt.log10(eps)) then psih=0. else zeta=z/l if (zeta.gt.0.) then psih = - (1.+0.667*a*zeta)**(1.5) - b*(zeta-c/d)*exp(-d*zeta) & - b*c/d + 1. else x=(1.-16.*zeta)**(.25) psih=2.*log((1.+x*x)/2.) end if end if end function psih